For folding frames in the prior art, the frame is usually horizontally rotated to fold, so that front and rear wheels are folded from left and right, thus reducing the space occupied. This folding manner requires fixation after the frame is unfolded so as to prevent sideway shaking in a riding process. Since vibration will occur in the riding process, a fixed structure is easy to loosen, so as to bring about safety risks. Moreover, the operation of the fixed structure is relatively complex, and is not beneficial to use. Furthermore, this folding structure lacks effective support in an unfolded state, and the stability thereof is relatively poor.